When diagnosing pulmonary foci or in the case of lesions of the mediastinum, frequently requires carrying out a biopsy of the affected region. It is only by the removal of tissue that it can be unambiguously established whether the lesion is benign or malignant, and which therapy measures need be taken, if appropriate. This is predominantly carried out percutaneously (through the skin). Disadvantages of this method are the low hit rate of centrally positioned lesions, together with the time consuming repetition, associated therewith and increasing the risk to the patient, of the procedure, as well as the so called pneumothorax, in which air penetrates through the thorax. The pressure arising at the lung complicates breathing and must be treated in many instances.
For this reason, lesions lying directly on the bronchi and that are of sufficient size are better biopsied transbronchially. In this case, use is made of a special bronchoscope having a channel for visualization and a working channel for removing a tissue sample. If the lesions on the inner bronchial wall can be identified, good results can be obtained thereby. On the other hand, uncertainty arises during the biopsy as to whether the lesion has really been hit. If the tissue sample removed is malignant, it is simultaneously an indication that the lesion has been hit. However, if this is not the case, either the lesion is benign or it has not been hit, and the biopsy must be repeated.
An improvement is delivered here by a method such as is proposed in document US 2006/0084860 A1. Here, imaging methods are used to carry out a segmentation of the bronchi, and thereby to produce a three-dimensional virtual image of the bronchi. During the carrying out of the bronchoscopy, the lesion on the inner surface of the bronchial wall is inserted on this three-dimensional virtual representation of the bronchi, and at the same time the current position of the bronchoscope is illustrated in the virtual three-dimensional representation. It is thereby possible to raise the hit probability during the bronchoscopy.
It is, however, disadvantageous in this method that a reliable biopsy is not yielded despite the insertion of the lesion on the inner bronchial wall. Particularly in the case of small lesions, or ones that lie very far removed from the bronchial wall, it is not possible to establish with certainty whether the lesion is benign in the case of a benign tissue sample, or simply has not been hit.